Which version of Exchange is NOT supported to be a hybrid server?

Which version of Exchange is NOT supported to be a hybrid server?

• 2016
• 2013
• 2010
• 2007

EXPLANATION

The version of Exchange you have installed in your on-premises organization determines the hybrid deployment version you can install.
You should typically configure the newest hybrid deployment version that's supported in your organization. For example, if your on-premises organization is running Exchange 2007, you need to configure an Exchange 2013-based hybrid deployment.

SOURCE

https://docs.microsoft.com/en-us/exchange/hybrid-deployment-prerequisites